1. Field of the Invention
This invention relates to a traction drive of a machine, in particular of an industrial truck, which has an internal combustion engine, a transmission module located downstream of the engine with an adjustable output speed, and a drive axle with a differential transmission which is in a mechanical drive connection with the transmission module.
2. Technical Considerations
DE 100 25 089 A1 describes a generic traction drive. On this traction drive, a continuously variable electric transmission is provided which has a generator and an electric motor connected to it. The generator and electric motor are interlocked with each other or are located in a common housing and therefore form a transmission module which on continuously variable transmissions of this type is also called a compact transmission. In contrast, a continuously variable transmission in which the principal components are separate from each other is called a “distributed transmission construction”.
In general, the type of traction drive used is essential in determining the construction, traction, and working capabilities of machines, in particular of industrial trucks (e.g., fork lift trucks). Industrial trucks with a traction drive that contain an electro-converter can of course have a traction capability which is similar to that of industrial trucks that are provided with a hydrostatic traction drive. Although, they can differ in terms of their construction, such as with regard to the location of the internal combustion engine, the realization of the drive axle, etc. For example, on the latter type of industrial truck, hydrostatic wheel motors are frequently used as the output-side components of the hydrostatic drive system, which in distributed transmission constructions are connected to a pump of the hydrostatic drive system. The pump is connected with the internal combustion engine.
In traction operation, industrial trucks with hydrodynamic converters and power shift transmissions differ from the construction described above with regard to their design, their traction, and work response. Compared to such industrial trucks, industrial trucks with a continuously variable transmission (e.g., electro-converter or hydrostatic drive system) frequently have advantages in terms of ease of traction operation.
Depending on the concept used in the design of the traction drive, different types of industrial trucks must therefore be developed and manufactured, which requires a significant investment of time, effort, and money.
Therefore, it is an object of this invention to provide a traction drive of the general type described above but that has an expanded range of operation.